Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden box covered with coloured paper with picture of Santa Claus on it (see Fig. 13.4). She must know the exact quantity of paper to buy for this purpose. If the box has length, breadth and height as 80 cm, 40 cm and 20 cm respectively how many square sheets of paper of side 40 cm would she require?

Explanation

To find out how many square sheets of paper Mary needs to cover the wooden box, we will follow these steps:

### Step 1: Calculate the Total Surface Area of the Box
The formula for the total surface area (TSA) of a rectangular box is given by:
\[ \text{TSA} = 2(lb + bh + lh) \]
where \(l\) is the length, \(b\) is the breadth, and \(h\) is the height.
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